Appendices & Glossary - Botanical Research Institute of Texas

1306 APPENDIX TWENTY-ONE/COMMERCIALLY IMPORTANT TIMBER TREES OF EAST TEXAS
CARYA TOMENTOSA (Lam. ex Poir.) Nutt. MOCKERNUT HICKORY
(JUGLANDACEAE, WALNUT FAMILY)
Other Common Names: WHITE HICKORY, HOGNUT, BULLNUT, FRAGRANT HICKORY, BIGBUD HICKORY, HARD-BARK HICKORY,
WHITE-HEART HICKORY.
Form and Size: large tree to 36 m; trunk straight, to 1.5 m in diameter, unbranched for about half its height in the forest or
widely branched and spreading in the open; crown shape highly variable.
Leaves: deciduous, compound, alternate, with (5–)7–9 leaflets per leaf; leaflets fragrant, having a spicy odor when
crushed, 4–22 cm long and 2–12.5 cm wide, the lower pairs slightly smaller than upper, symmetrical (not falcate), the
upper surfaces dark yellow-green, the lower surfaces velvety to the touch.
Buds: terminal buds tan (after early loss of reddish brown outer scales), broadly ovoid, very broad at the base, 8–20 mm
long, tomentose; bud scales 3–4, imbricate (= overlapping); axillary buds about half the size of the terminal bud, protected
by bracteoles fused into a hood.
Flowers: flowers unisexual, the male and female flowers on same tree (plants monoecious), appearing with the leaves in
spring, inconspicuous, without corollas; male flowers usually with 4 stamens, in stalked, 3-clustered, light green catkins
10–15 cm long; female flowers 2–5 on short spikes at the ends of new branches.
Fruits: occurring singly or in small clusters, spherical to ellipsoid or obovoid, 30–50 mm long and almost as wide, with
husk ca. 3–15 mm thick splitting to expose the nut; nuts tan, spherical to ellipsoid, prominently to faintly 4-angled, the
shells usually very thick, the kernels sweet.
Bark: dark gray or brownish and relatively thin with a crisscross or net-like pattern of shallow furrows and flat narrow
ridges, close (not shaggy).
Wood: sapwood whitish to pale brown, wide; heartwood pale brown to brown, or reddish brown; wood straight-grained,
very hard; growth rings distinct.
Habitat: well-drained sandy soils, typically in uplands (particularly on Ultisols = deeply weathered, somewhat infertile,
acidic soils).
Range: Pineywoods and northeastern Post Oak Savannah, also Gonzales Co. and northern Gulf Prairies and Marshes;
widespread in the eastern half of the U.S. west to IA and TX.
Principal Uses: the wood is among the best produced by hickories, with excellent hardness, strength, shock resistance,
bending, and compression qualities; as a result uses include tool handles (especially hammers, axes, and sledges), ladders,
gymnastic bars, poles, agricultural implements, and dowels. Other uses include lumber, pulpwood, veneer, rustic
furniture, wood splints, woodenware and novelties, charcoal, and firewood; sawdust, chips, and some wood is used to
smoke meats; even the nuts can be soaked in water and used without the husk in fires to give food a hickory-smoked
flavor.
Historical Uses: tool handles, agricultural implements, fuel wood because of high caloric/heating value, skis; early settlers
in the northern U.S. extracted a black dye by boiling small pieces of bark in a vinegar solution. Native Americans used
the species as an analgesic.
Other Significant Information: because of its wood, HICKORY was a symbol of strength in the pioneer mind, and
MOCKERNUT HICKORY was among the strongest. The species is long-lived, with individual trees surviving up to 500
years. The nuts are tasty but hardly worth the effort needed to extract them from their hard thick shell—the common
name MOCKERNUT apparently resulted from the difficulty of removing the sweet but small kernels. The genus Carya
has a fascinating worldwide distribution, being known from only two areas: eastern North America (including East
Texas) and eastern Asia. In the distant past (e.g., 30 million years ago during the mid-Tertiary Period), under very different
conditions (e.g., sea level, temperature, continental arrangement), dispersal of plants and animals between the Eurasian
and North American continents was possible. The fossil record shows that many plants had extensive distributions
across the Northern Hemisphere—for example, temperate forests with tropical elements occurred very broadly,
with similar floras known widely from North America, Europe and Asia. There have been great geologic and climatic
changes over millions of years and many once widespread plants have become extinct in all but one or a few places—
Carya is an example. This species, which is the most common hickory in the southern U.S., has sometimes gone under
the scientific name Carya alba (L.) Nutt. ex Elliott. However, many recent authors, such as Stone (1997 in Flora of North
America), treat the species as C. tomentosa. According to Stone (1997), “Both the mockernut hickory and the shagbark
hickory were formerly known as Carya alba (L.) K. Koch [or Hicoria alba (L.) Britton], based on Juglans alba of
Linnaeus. A.J. Rehder (1945) pointed out that the original circumscription included two taxa, and C. alba (J. alba)
should therefore be rejected as ambiguous in favor of C. tomentosa and C. ovata, respectively.”
Recognition in the Field: alternate, odd-pinnately compound leaves with (5–)7–9 leaflets per leaf, the leaves fragrant, with
a spicy odor if crushed, the leaflets velvety to the touch beneath; fruit hard, nut-like, covered by a husk 3–15 mm thick
that splits vertically into 4 sections; bark not shaggy.